Dial protractor



H. F. SEMRAU DIAL PROTRACTOR Jan. 24, 1950 2 Sheets-Sheet l Filed NOV. 6, 1945 lll Jan, 24, 1950 H. F. SEMRAU DIAL PRoTRAcToR 2 Sheets-Sheet 2 Filed Nov. 6, 1945 INVENTOR.

Patented Jan. 24, 1950 DIAL.Y PRO TRACTOR.1 HugolF. Semrau,y Verona; .PatA

Application November 6, 1945, Serial No. 626,

This invention relates to improvements in dial protraciors; for: accurately, measurinay 01H4 laying Outianglesaoffwor One Y.. of, the objects, ofthe: present invention sto proyide a dial. protractorA-bymeans gof which angular measurementsof objects canbe quicklyl and ,extremely accurateand .directly obtained.

Another object of theinvention is. to provide an-instrumentlwith, a circular dia1 furnished with a vernier y in which` the graduations are greatly enlarged-so that accurate-readings of angular measurementsmay-behacl aid of a magnifying glass.

Still another. Volciect -ofthe inyention is to pro..- vde'azdial prutractor bygmeansof u'hiclirullanales mayybe .measured fr0m.=the, vertex-i Yetanotherfobject of the-,invention is .togphro-A vide a dial protractor which-xis .capalele;toinefv adjustment by ordinary fmanuai manipmation.

Anothen objectI of the..inventi sion -of rounolv barsV on which the maybe shifted, thereby .providin but very accurate sliding mechanism.

Stilll another object yof lthe invention :is-to .providea dial protractorwiljlhl a me and i nneadjustment operable froin af; unitary.; source and means for loghi-nas position.

Another object qof -the invention is v`to provider a dial protractorwhich iscompact, lightinweight 30 20,: aa gfal. mechansln hDllSIl and of asize:favorablewith` instrumentsI in every da] g2?, alslidilng .edg923 and a day/ruse, dustfproof easy to manipulate; extreme- Basal!) CQIIIPJISEBSf'171162. Da 1y accurate, readable directly `'and inexpensive to 11911511.11@ .SllppOlib end.. 25 imp. manufacture.` gated,.nar.a1.1el .Slidingz-.edaefen To the aceomplishmentof-these Lai1 dsucliv other 35 rims?? Ofc-th@ fOlmSrfiSeDyOi/i objectsaamay hereaftenappear the; invention @$10135 2r-arollldithecsemi consists ofthe novel construction,combination; Saidilmi" adalbeditiben andafrangement 0f partsfheren specifically cle- S1'1`215Q11S-A 29 0f .1 a-. DIIOII scribed; 'andi illustrated'ingthe jdrayviilgs,V wherein-A knQbpeXiiQIlSOn ,3 I i The baise:- Zf S is snowman yembodiment lof thel invention, but; 40 With..Uhren 0r;more.-.1ees

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2,',3aand 6, a studf cured to. a measuringfeclge17^ ;one. enel*4 of. which is :provided centric. relation witlristudff. has fsecurecl; thereon in any :upwardly eXte urillgiedgefisise e teeth offarmllis apin- \-.-.carries;;a-igear y3H .in mesh with :the

the:y upwardly extending riding postf. cured;

Thelower end- 0f the? ted f by thev numeral i The aforesaid pinion 30, including the integral knob-extension 3| is suitably mounted for free rotation and is adapted to be inor out of mesh with the iine serrations 28 of the rim 21 at a suitable angle on one end of the bracket 42, while the opposite end terminates into a pair of ears 43, the free ends of which terminate into a cam-edge 44. It will be noted that the stud 33 is shown peened over at the shoulder as indicated by the numeral 45 in order to be prevented from turning on the measuring-edge arm 34.

A hair-spring 46, one end of which is secured to the bushing 41 and the other end of which is secured to a pin 48 is secured to the measuringedge arm 34. This pin 43 moves in an arcuate slot 49 (Figure 1) of the gear housing 50 in order to adjust the tension of the same.`

The said hair spring 46 serves to absorb the play or backlash of the gear train 35, 31, 38 and 39. The inner end of the hair spring 46 is secured to the bushing 41 in any suitable manner. The outer end of hair spring 46 is fastened to pin 48, which is screwed in arm 34 and is free to move in arcuate slot 49. By turning the arm 34 a quarter turn in counter-clockwise direction, the hair spring 46 opens or decreases its tension, but on account Aof the I to 8 ratio of the gear train the inner end of the hair spring is wound with two turns, thereby increasing its tension and absorbing the backlash or play of thc train of gears.

The bifurcated lower end of stud 33 and the cam-ears 43 have a common stub-shaft 5| as will be understood. Underneath said cam-ears 43 is secured thereon a flat U-shaped springmember 52, the free end of which is in contact with stub-shaft as best shown in Figures 2, 3 and 4.

The angular movement of the measuring edge 24 is transmitted by the arm 34 to pinion 31 and gears 38 to pinion 39 which carries the hairspring 46 and a graduated dial 53. This'dial is divided into 45 equally spaced graduations in which each line represents one degree and is marked with two sets of figures, one reading from 0 to 45 degrees and the other one from 45 degrees to 90 degrees.

The ratio, for an example as shownv in the drawing, of the measuring-edge arm segment 54 to pinion 39 is l to 8 that is, degree movement of the measuring-edge 24 is indicated at the zero line 55 in Figure l by two full turns of the graduated dial 53; a 45 degree movement of the measuring-edge 24 is indicated at the zero line 55 by one full turn of the graduated dial 53, thus the graduation on dial 53 indicates the angular movement and position of the measuring edge 24 on an enlarged scale. A Vernier scale 56 is also provided for sub-dividing one degree in tenths of a degree or 60 minutes.

At this time, attention is called with the wide apart graduations of the Vernier scale and Ythe dial graduations of the instrument which is one of the important features of this invention.

The measuring-edge unit 51 rotatably mounted on stud 33 is limited to a quarter turn onlyr and any position within this quarter turn can be accurately locked by manipulating the pinion 30 of the locking and ne adjustment mechanism 58. y

The sliding-edge mechanism 59 consists of a cylindrical bar 60 centrally secured to the slidingedge end 26 of the base 20 by means of screws 6l on which is slidably mounted the upright slidingedge post 62 through the aperture 63, open at the a quarter turn or 90 i the knob 3l of.

Cir

measuring-edge 24 'consequently is adapted to lowermost end 64 shown in Figure 9; this aperture 63 has a correlated, parallelly disposed aperture 65 and both apertures 63 and 65 have a common slotted portion 66 So as to permit clamping of the post 62 around the bar 60 in any desired position by means of clamp-screws 61.

The upper portion 68 of post 62 also has a pair of horizontal apertures 69 and 10 in which aperture 69 is adapted to receive the cylindrical bar 1| secured to the underside of the slidingedge 23. It is to -be noted, that apertures 63 and 65 at the lower end of post 62 and the apertures 69 and 10 at the upper end of post 62 are located at right angles or perpendicular to each other.

The sliding-edge 23, preferably L-shaped as shown, is provided with graduations 12.

Between apertures 63 and 65, and 68 and 10 clamping screws 61 and 13 are provided which serve to tighten the post 62 to sliding bar 60 and 1l respectively in anydesired perpendicular position.

The movement of the sliding-edge 23 in perpendicular directions permits contacting the at any angular position and measure any angle from the vertex, and by moving the sliding-edge 23 away from the measuring-edge 24 any magnitude of an angle may be readily measured.

Both, the sliding-edge and the measuring-edge are provided with inch graduations 12 and 14 respectively thereby providing means for measuring or inspecting the length of tapers or shoulders of angular objects.

As heretofore mentioned the magnification of the graduation of the dial protractor herewith described is based on a ratio of 1:8 but it will be understood that other ratios may be employed to obtain the same results.

The graduated dial 53 shows the graduations expressed in degrees, of course it is obvious that the graduations may be expressed in taper per inch or foot, Morse, B & S or Jarno taper etc. if desired.

The gear housing 50 is provided with a cover or lid 15 of transparent material in which approximately 3A; of its area is masked off showing only about 1/4 of the graduated dial 53 including the Vernier 56. A pointer 11 is shown secured to post 36 pointing to the graduations on cover 1 and mainly serving to roughly and rapidly set the angular position of the measuring edge 24 after which the exact angular position is set by means of the fine adjusting mechanism 58.

The present invention contemplates the provision of means to effect first, a rough or approximate setting of the desired angular position of the measuring-edge 24,`and second, thc final or ne and accurate position of the measuring-edge 24. Both, the rough and accurate set- 3| and pinion 30, the latter being rotatably mounted on the knobextension which is secured tothe bracket 42. The rough and accurate settings are effected in the following manner It is assumed that the sliding edge 23 is in the desired position, next, the measuring-edge 24 is rough set into an approximate angular position by slightly forcing the knob 3l downwardly thereby causing the pinion 30 to be brought out of mesh of the normally engaged serrated rim 21 of the housing support end 26 of base 20. The bracket 42 of the fine adjustment mechanism 58 pivots on stub-shaft 5l supported in the bifurcated end 4I of stud 33. One end of the U-shaped nat spring 5I is secured tothelundersideof the pin; said sliding edge having secured to the underside thereof and in parallel alignment with the sliding edge an elongated cylindrical bar; a post, provided at the upper and the lower ends with horizontally disposed apertures positioned at right angles to snugly receive the cylindrical bars of said base and said sliding edge; said apertures being open at the top and bottom, said post having correlated, parallel apertures and slots to permit clamping of the sliding edge to said post by means of clamping-screws; said measuring edge mounted to be moved in angular positions in respect to said sliding edge; a rotatable dial, indicating equal degree divisions, mounted on the uppermost portion of the center-pin of said stud and in cooperation with a fixed Vernier scale on said housing for measuring a fractional part of one of said divisions; a train of gears in said housing, a protractor arm i-lxed on said stud, one end secured to said measuring edge and the other semi-circular end thereof being provided with peripheral gear teeth in mesh with said train of gears by means of which said dial is rotated at a certain ratio in respect to the angular motion of said measuring edge; unitary means for oscillating the measuring edge about said stud and rotating said dial about said center-pin and means for locking the measuring edge by said unitary means in any desired angular position.

4. A dial protractor comprising a base; a pair edges normally disposed opposite each other and both movably mounted on said base; one of said edges serving as a sliding edge and the other one serving as a measuring edge for measuring the degree of angles; a gear-housing mounted on said base provided with a central stud having a center-pin; means for guiding said sliding edge for movement in radial alignment with said centerpin and a perpendicular direction with respect to the sliding base edge end of said base; said guiding and sliding means comprising an elongated cylindrical bar secured to the upper face of said base in radial alignment with said center pin; said sliding edge having secured to the underside thereof and in parallel alignment with the sliding edge an elongated cylindrical bar; a post provided at the upper and the lower ends with horizontally disposed apertures positioned at right angles to snugly receive the cylindrical bars of said base and said sliding edge; said post having correlated parallel apertures and slots to permit clamping of the sliding edge to saidpost by means of screws said measuring edge mounted to be moved in'angular positions in respect to said sliding edge; a rotatable graduated dial in cooperating with a xed Vernier scale on said housing for measuring a fractional part of one 'of said graduations of said dial; a protractor arm having one end secured to a post provided with a pointer and on which the measuring edge is mounted and the other semi-circular end of said protractor arm being provided with peripheral gear teeth in mesh with a train of gears by means of which the dial is being rotated at any desired ratio in respect to the angular motion of said measuring edge; a transparent cover for said gear-housing on which a three-quarter sector is masked off so as to expose only a quarter sector of the dial including the Vernier scale; graduations indicating degrees marked on said masked oi sector cooperating with said pointer secured to said protractor arm post to indicate the movement in degrees of said measuring edge; means for oscillating the measuring edge for rough or tine measuring of angles and means for locking the 'measuring edge in any desired position by said oscillating means.

5. A dial protractor comprising a base; a pair cf edges normally disposed opposite each other and both movably mounted on said base; one of said edges serving as a sliding edge and the other one serving as a measuring edge for measuring the degree of angles; a gear-housing mounted on said base provided with a central stud having a center-pin; said sliding edge mounted for guiding in radial alignment with said center-pin and in a perpendicular direction with respect to the sliding base edge end of said base; said guiding accomplished by means of an elongated bar secured to the upper face of said base in radial alignment with said center pin; said sliding edge having secured to the underside thereof and in parallel alignment with said sliding edge an elongated bar; a post provided at the upper and the lower ends with horizontally disposed apertures positioned at right angles to snugly receive said elongated bars of said base and said sliding edge; said post having correlated parallel apertures and slots to permit clamping of the sliding edge to said post by means of screws; said measuring edge mounted to be moved in angular positions in respect to said sliding edge; a rotatable, graduated dial disposed in said gear housing and secured to said center pin for indicating iine or micrometric angular measurements in cooperation with a fixed Vernier scale mounted on the rim of said gear housing for measuring a fractional part of one of the graduations of said dial; a train of gears mounted in said housing; means to greatly enlarge the spaces between the graduations of said'dial to facilitate reading of the measurements, said means consisting of said train of gears between the measuring edge and the dial; a cover for said gear-housing exposing only a quarter sector of the dial including the vernier scale; a protractor arm provided with an upright post having one end secured to said post on top of which said measuring edge is mounted and the other semi-circular end of said protractor arm being provided with peripheral gear teeth in mesh with said train of gears; graduations indicating degrees marked on the exterior of said cover in cooperation with a pointer secured to said upright post to roughly indicate in degrees the movement of the measuring edge; means for oscillating the measuring edge for rough or iine measuring of angles and means for locking the measuring edge in any desired position by said means.

6. A dial protractor comprising a at base; a pair of edges normally disposed opposite each other and both movably mounted on said -at base; said base having an enlarged semi-circular extension provided with peripheral serrations; one of said edges serving as a sliding edge and the'other one serving as a measuring edge; a gear-housing mounted on said semi-circular extension; a train of gears and a central stud in said housing; a protractor arm having one end secured to an upright post on which said measuring edge is mounted and the other semi-circular end of said protractor arm being provided with peripheral gear teeth in mesh with said train of gears; said stud having an upstanding centerpin and a biiurcated depending extension secured to said protractor arm, said extension arranged below the underside of said base; a graduated dial secured to the uppermost portion of said center-pin and a bracket having one end provided with cam-ears pivoted on a stub-shaft on said bifuroated stud extension and the other end of said bracket provided with a rotatably mounted combined knob and serrated pinion extending outwardly of said base and adapted to selectively engage or disengage the serrations of said base; a washer loosely engaging the depending end of said stud in abutment with the underside of said base and adapted to be in or out of frictional contact with said base and camears of said bracket; a. spring secured to the camear end of said bracket and in contact with the underside of said stub shaft; said serrated pinion normally held in mesh with the semi-circular, serrated portion of said base for fine or micrometric measuring by turning the serrated pinion 15 knob; a cover for said gear-housing having graduations indicating degrees for rough measuring marked on top of the same, said graduations in cooperation with a pointer secured to the upright post of said protractor arm to which the measuring edge is mounted; said serrated pinion brought out of engagement with the serrated portion of said base by a. slight downward push of l 0 the pinion knob after which said knob is oscillated until the pointer indicates the rough angularposition of the measuring edge and means for locking the latter in any desired position.

HUGO F. SEMRAU.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS 

